This invention relates generally to lift platforms and in particular to platforms for lifting passengers in wheelchairs onto a public conveyance or other vehicle and which is also retractable into the floor of said vehicle.
The lifting platforms of the prior art generally include various configurations comprising a generally horizontal platform which is raised and lowered on the outside of the vehicle using a parallelogram arrangement to maintain the platform in the horizontal position and other devices which cause the platform, after it is raised, to be folded vertically either inside the vehicle or immediately outside the vehicle.
In some cases the lifting and lowering mechanism is attached to the underside of the vehicle however the platform itself when retracted is folded up against the outside of the vehicle.
Some devices even go so far as to provide hinges in the platform for it to articulate and fold up inside the cab of the vehicle. In other cases the door of the vehicle is used as the lifting platform such that it remains horizontal when lifting the passenger onto the vehicle and then converts to the vertical position and closes as a door in the side of the vehicle.
All these prior art devices have the disadvantage of occupying a space within the interior of the vehicle or projecting from the exterior of the vehicle or requiring special design for each vehicle in which they are installed.